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Can PLA plastic be injection molded?

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PLA can be injection molded, and many flowerpot-type products have begun to gradually use PLA materials instead.

PLA is regarded as the most promising green material in this century because of its good injection molding processability, superior biodegradability, and vegetable raw material source.

Although PLA can be treated as a general-purpose resin, there are still some unique features in the injection molding process of PLA compared with other general-purpose resins.

What is PLA and why is it used in injection molding?

PLA has high strength without curling, very low shrinkage (0.3%) environmentally friendly material, is 100% degradable by composting, has excellent molding performance, has stable thermoforming scale, good adhesion between layers, and also possesses good glossiness.

PLA has good thermal stability, a processing temperature of 170-230℃, good solvent resistance, can be processed in many ways, is easy to process, and has very wide application. Such as extrusion, and injection molding. Products made from PLA are biodegradable in addition to good biocompatibility, gloss, transparency, hand feel, and heat resistance.

PLA material characteristics

1. PLA is a new type of biodegradable material made from starch plastic composites and raw materials from renewable plant resources (such as corn).

Glucose is obtained by glycation of starch raw materials, then high purity lactic acid is made by fermentation of glucose and certain strains of bacteria, and then PLA of certain molecular weight is synthesized by chemical synthesis method.

It has good biodegradability and can be completely degraded by microorganisms in nature after use, eventually generating carbon dioxide and water without polluting the environment, which is very beneficial to the protection of the environment and is recognized as an environmentally friendly material.

The treatment method of common plastics is still burning and cremation, which causes a lot of greenhouse gases to be discharged into the air, while PLA plastic is buried in the soil to degrade, and the carbon dioxide produced directly enters the soil organic matter or is absorbed by plants, which will not be discharged into the air and will not cause the greenhouse effect.

2. Good mechanical properties and physical properties. PLA is suitable for various processing methods such as blow molding, thermoplastic, etc. It is easy to process and very widely used.

It can be used to process various plastic products from industrial to civil, packaged food, fast food lunch box, non-woven fabric, and industrial and civil cloth.

In turn, it can be processed into agricultural fabrics, health care fabrics, wipes, sanitary products, outdoor UV protection fabrics, tent fabrics, floor mats, etc. The market prospect is very promising.

3. Good compatibility and degradability. PLA is also widely used in the field of medicine, such as disposable infusion appliances, non-removable surgical sutures, etc., and low molecular PLA is used as a drug slow-release packaging agent, etc.

4. In addition to the basic characteristics of biodegradable plastics, PLA also has its unique characteristics. The strength, transparency, and resistance to climate change of traditional biodegradable plastics are not as good as those of ordinary plastics.

5. PLA has similar basic properties to petrochemical synthetic plastics, which means that it can be used in a wide range of applications. PLA also has good gloss and transparency, comparable to films made from polystyrene, which are not available in other biodegradable products.

6. PLA has the best tensile strength and ductility, and PLA can also be produced in a variety of common processes

For example, melt extrusion, injection molding, blow molding, foam molding, and vacuum molding have similar forming conditions to widely used polymers, and it has the same printing properties as conventional films.

In addition, it has the same printing properties as conventional films. In this way, PLA can be used in a variety of applications to meet the needs of different industries.

7. PLA film has good air permeability, oxygen permeability, and carbon dioxide permeability, and it also has the property of isolating odor.

Viruses and molds are easily attached to the surface of biodegradable plastics, so there are safety and health concerns, however, PLA is the only biodegradable plastic with excellent anti-bacterial and anti-mold properties.

8. When incinerating PLA, its burning calorific value is the same as incinerating paper, which is half of incinerating traditional plastics (such as polyethylene), and incinerating PLA will not release toxic gases such as nitrogen compounds and sulfides.

The human body also contains lactic acid in monomer form, which indicates the safety of this decomposable product.

PLA injection molding mold requirements

When injecting and molding PLA resin, there are certain requirements for the mold, which include: the cooling effect of the mold should be good and must be equipped with a water chiller, such as a 200g injection molding machine with a 2kW water chiller.

Since the injection speed of thick-walled products is relatively slow compared with that of thin-walled products, the mold should be designed to control the thickness of the products below 4mm, and the core, cavity, or front and rear templates and sliding blocks of the mold need to be cooled by passing water, and the temperature of the mold needs to be controlled between 20~30℃.

PLA drying conditions

PLA resin must be dried before use. To prevent the decrease of melt viscosity, the humidity should be controlled at 0.025% (250ppm) or less.

Typical drying conditions are: air temperature 80°C, air dew point -40°C, air flow rate >1.85m3/h-kg, and drying for 2-3hrs; or air temperature 80°C and vacuum drying for 2-3hrs.

The dried resin should not be exposed to the air and should be placed in nitrogen-filled aluminum foil bags, plus boxes or bags for protection. The package should be kept sealed before use, and the unused material should be sealed quickly after use.

If the material is exposed to the air for more than 1h, it needs to be re-dried as described above.

It should be noted that an in-line drying and dehumidifying machine must be used in production to ensure that PLA resin added to the hopper does not absorb moisture during the process.

PLA injection molding process

Cleaning the injection molding machine with low-viscosity polystyrene or polypropylene before injection of PLA resin, and then maintaining the temperature at a steady state.

Ensure that the air humidity in the filling hopper reaches below the dew point -40°C and that dust contamination is avoided; subject to the above conditions, pour PLA resin into the injection molding machine; and finally adjust the equipment temperature to the processing temperature of PLA resin.

During the PLA injection molding process, if you need to stop the machine for a short time (usually within half an hour), make sure to seal the baffle plate at the bottom of the hopper first, and then empty the remaining material in the barrel to prevent the feeding throat from being blocked.

When it is confirmed to start production again, only open the baffle plate to add material. If there is discoloration and degradation of material during processing, empty the barrel storage immediately, then add new material and observe the state of material to see if it is back to normal.

If normal can continue production; if not normal, make the corresponding adjustment. When you need to shut down the machine after production, use high viscosity polystyrene or polypropylene to clean the machine.

How does PLA compare to other conventional plastics when it comes to injection molding?

PLA is a plastic made from renewable resources, such as corn starch. PLA is biodegradable, making it an attractive alternative to traditional plastics. For injection molding, PLA has a lower melting point than other plastics, and it can be more brittle.

Therefore, it is not suitable for all applications. However, PLA can be blended with other materials to improve its properties.

For example, adding cellulose fibers can help increase the strength of the finished product. Overall, PLA is a promising injection molding material, but further research is needed to develop blends suitable for all applications.

What are the benefits of using PLA in injection molding projects?

PLA is a biodegradable plastic derived from renewable resources, such as corn starch, and wood-plastic composites PLA has many advantages over traditional petroleum-based plastics, making it an attractive option for injection molding projects.

PLA can be compounded with biodegradable thermoplastic elastomeric materials to modify the physical properties of PLA without compromising its compostability. 

One of the biggest benefits of using PLA is that it is more environmentally friendly than other types of plastics. PLA can be composted in commercial facilities, which means it will eventually break down into natural substances such as water and carbon dioxide.

In contrast, petroleum-based plastics can take hundreds of years to break down. PLA is also much safer to produce than other plastics. The production of PLA emits far fewer greenhouse gases than the production of other plastics and does not require the use of toxic chemicals.

Therefore, using PLA can help reduce your company’s impact on the environment. Finally, PLA is stronger and more durable than many other biodegradable polymers plastics. It can be used in a wide range of applications, making it a versatile material for injection molding projects.

How can you determine if PLA is the right plastic for your project needs?

PLA is becoming a popular choice for eco-conscious consumers. However, PLA has some drawbacks that you should consider before choosing it for your next project. In contrast to the cooling process from a melt below the glass transition temperature to a lower temperature, PLA crystallization is a slower process.

First, PLA is not as strong as other plastics, so it may not be suitable for projects that require a high degree of durability.

Second, PLA can be difficult to work with, so it may not be the best choice for beginners.

Finally, PLA is more expensive than some other plastics, so you’ll need to factor that into your budget.

If you are looking for an environmentally friendly option that is relatively easy to use, PLA may be the right plastic for your needs.

However, if strength and affordability are your top priorities, you may want to choose another type of plastic.

How can I determine if PLA plastic is the best choice for your project needs?

To answer this question, it is best to first understand what PLA plastic is and how it is made. PLA is different from other thermoplastic components in that PLA can be broken down by microorganisms, making it a more environmentally friendly option.

In terms of its properties, PLA is a strong and rigid plastic that can be used in a variety of applications. It also has a low melting point, making it easy to process. When choosing a material for your project, it’s important to consider the properties that are most important to you.

If environmental friendliness is a priority, then PLA may be the best choice. However, if you need a more flexible material, then PLA may not be the best choice. Ultimately, the decision on which material to use depends on the specific needs of your project.

Recycling of PLA plastics recycled material

There are two ways to recycle and dispose of recycled PLA resin: one is to crush it directly during the production process and transfer it to the hopper by automatic loading to be mixed with the new material.

This way is recommended for users because it is more efficient; the other way is to accumulate and store, then crush and dry uniformly afterward, and then mix with the new material.

Note: The drying condition of recycled material is different from that of new material, the residence time needs to be extended to 4~6hrs and the air temperature needs to drop to 45℃.

What are the applications of PLA materials?

Plastics have been widely used in agriculture, the plastics industry, construction, packaging, and other fields. In our daily life, we cannot live without a variety of plastic products. However, with the need for environmental sustainability, the plastic ban is gradually proposed and implemented.

At the same time, PLA raw materials have slowly started to enter the market and are being used more and more widely. PLA has good biocompatibility, degradability, and bio-absorbability, and has been used in medical materials, hygiene products, agriculture, packaging, fast consumables, and other fields.

Among them, food packaging and disposable tableware are the largest markets for its application. Due to the low consumption of plastic monomers, ease to cause pollution, and difficulty to separate efficiently, it makes biodegradable plastics more likely to be a substitute for traditional plastics in these fields.

Summary

PLA material is the most promising green material in this century. PLA is a new type of biodegradable material made from starch raw material proposed by renewable plant resources such as corn.

How to get satisfactory PLA products, injection mold factories about PLA material injection mold design, and PLA injection molding product production has put forward higher requirements.

Many injection molder factories have not been exposed to this material, if you have a PLA injection molding material-related project to do, you can seek the help of ZetarMold, we already have a wealth of experience in PLA material injection mold and plastic injection molding product production.

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